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    ABSTRACT: Biomass burning activity captured attention of the scientific community because of its significant impact on global climate change. In this paper, we present the results of a study of variations in aerosol optical, microphysical and radiative properties during the occasions of biomass burning at an high-altitude rural station, Sinhagad (18° 21′ N, 73° 45′ E, 1450 m AMSL), employing ground-based observations of MICROTOPS-II and short-wave (SW) Pyranometer, as well as satellite (MODIS) measurements of AOD during 28 April 2011 – 06 May 2011. Vertically resolved feature mask images from CALIPSO during night-time on available days are utilized as an additional tool to monitor the smoke/dust vertical distributions. A prominent smoke/dust layer is observed between 2 and 4 km altitude, while the CALIPSO observations of the vertical profile of aerosols are in qualitative agreement with values of MODIS-AOD550 nm. During the smoke/dust event, a drastic increase (∼0.9) in Terra/Aqua MODIS AOD550 nm is observed. Satellite data indicate a long-range transport of aerosol particles from Indo-Gangetic Plains (IGP) over large regions. The observed short-wave solar flux at the bottom of the atmosphere (BOA) is found to decrease due to aerosol extinction and was found to be −25 and −16 Wm−2 for the aerosol laden days and normal days, respectively. In addition, the transport of a wide spread forest fire plume is observed across the country as evidenced by the MODIS imagery and HYSPLIT back trajectories. The observed features are also explained on the basis of the results from the NCEP/NCAR and ECMWF re-analysis data.
    Journal of Aerosol Science 06/2014;
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    ABSTRACT: h i g h l i g h t s Similar variation of OC and EC in all seasons. Both SOC and POC almost equally contributed to form OC. Dominance of POC and EC in post-monsoon and winter. A new term Effective carbon ratio in place of conventional OC/EC.: Organic and elemental carbon OC/EC ratio Primary and secondary organic carbon Effective carbon ratio a b s t r a c t Increasing emissions from fossil-fuel, biomass burning, land use changes and industrial growth have led to rapid increase in the atmospheric concentrations of carbonaceous species over many cities in India. The present paper deals with the results obtained from year long (2012e13) observations conducted at a tropical urban location, Pune in southwestern India on Organic and Elemental Carbon as well as Black Carbon; using the Sunset OCEC Analyzer and Aethalometer, respectively. The average mass concentra-tions of OC and EC were in the order of winter > post-monsoon > summer > monsoon. Mean annual OC/ EC ratio was found to be 2.4 AE 1.1 during the study period, suggesting the presence of secondary organic carbon (SOC). Estimated SOC was found to form 47% of OC mass concentration. OC and EC were also significantly well correlated (r ¼ 0.95, p < 0.0001) to each other, indicating towards common combustion sources. The primary organic carbon (POC) dominated over SOC and EC in post-monsoon and winter seasons indicating impact of anthropogenic burning activity, enhanced by prevailing meteorological conditions as well as that of long range transport. Mean annual POC þ EC/TC ratio was 0.69 indicating that more than 2/3 of TC is formed from combustion sources. Thermally derived EC and optically derived BC correlated very well (r ¼ 0.98, p < 0.0001). A new concept e.g. Effective carbon ratio (ECR) is suggested to better assess the scattering/absorptive nature and probable source identification of carbonaceous aerosols in place of conventional OC/EC ratio.
    Atmospheric Environment 05/2014; 92:493-500.
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    ABSTRACT: Atmospheric Infrared Sounder (AIRS) retrieved mid-tropospheric Carbon Dioxide (CO2) have been used to study the variability and its association with the climatic parameters over India during 2004 to 2011. The study also aims in understanding transport of CO2 from surface to mid-troposphere over India. The annual cycle of mid-tropospheric CO2 shows gradual increase in concentration from January till the month of May at the rate ~0.6ppm/month. It decreases continuously in summer monsoon (JJAS) at the same rate during which strong westerlies persists over the region. A slight increase is seen during winter monsoon (DJF). Being a greenhouse gas, annual cycle of CO2 show good resemblance with annual cycle of surface air temperature with correlation coefficient (CC) of +0.8. Annual cycle of vertical velocity indicate inverse pattern compared to annual cycle of CO2. High values of mid-tropospheric CO2 correspond to upward wind, while low values of mid-tropospheric CO2 correspond to downward wind. In addition to vertical motion, zonal winds are also contributing towards the transport of CO2 from surface to mid-troposphere. Vegetation as it absorbs CO2 at surface level, show inverse annual cycle to that of annual cycle of CO2 (CC-0.64). Seasonal variation of rainfall-CO2 shows similarities with seasonal variation of NDVI-CO2. However, the use of long period data sets for CO2 at the surface and at the mid-troposphere will be an advantage to confirm these results.
    Science of The Total Environment 01/2014; 476-477C:79-89.

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